The present invention relates generally to an apparatus and method for infusing fluids into the body and more specifically to an inline fluid warmer.
It is understood that when introducing fluids to the body it is desirable to maintain the fluids generally at a temperature approximating the body temperature. It has been recognized that the introduction of fluids into the body at temperatures below the body temperature at high flow rates can induce hypothermia or shock. Additionally, it has been recognized that healing periods are increased in certain circumstances when fluids are introduced to the body that are below the body temperature.
Devices have been developed that are used to warm fluids prior to their infusion into the body. Two basic types of devices are used for warming fluids.
Bulk fluid warmers are known that warm the entire fluid volume to a specified temperature prior to the infusion. This type of fluid warmer requires that the warming process be initiated sufficiently in advance of the infusion to allow the fluid to be heated to the desired temperature. The requirement that the entire volume of fluid be warmed in advance of use makes this type of unit less desirable in certain applications, such as in emergency and trauma circumstances where the delay in infusing fluids could be potentially harmful or life threatening to a patient. Additionally, bulk fluid warmers are typically large fixed units that are not readily portable. Thus, the use of these devices is generally relegated to a fixed location. Moreover, once the fluids are warmed in bulk, the warmed fluids are typically transferred to and hung on an IV pole and delivered through a standard IV line which is around six feet in length. At low flow rates, the warmed fluids that exit the fluid container cool while traversing the IV line to the patient. Additionally, bulk fluid warmers are not suitable for use with some fluids that degrade if they are heated in advance and held at an elevated temperature for a prolonged period.
Inline fluid warmers have also been developed in an attempt to overcome some of the problems associated with bulk fluid warmers. An inline fluid warmer is a device that warms the fluid to be infused in the delivery line between the fluid source and the point of infusion into the body. Two general classes of inline fluid warmers are known.
One class of inline fluid warmers warms the fluids in the delivery line itself as the fluid passes through the delivery line. Such devices tend to be usable only at low flow rates since intravenous (IV) tubes are typically poor thermal conductors and it is difficult to efficiently transfer heat to a fluid passing through conventional IV tubes.
Another class of inline medical fluid warmers is interposed in the IV line set between the fluid source and the patient. Such devices warm the fluid to a desired temperature within the warming unit as the fluid passes through it. Such devices are more suitable for portable or field application and may be provided with a short output delivery tube to minimize the temperature drop in the fluid between the output of the inline fluid warmer and the infusion site. Such devices are also capable of use at high flow rates. Examples of these types of devices are disclosed in U.S. Pat. Nos. 6,142,974, 6,175,688, 6,336,003 6,236,809.
It would therefore be desirable to have an improved medical fluid warmer of small size that could be used either in operating room, clinical or field environments. It would further be desirable for the device to be cost effective to manufacture to promote the wide deployment and use of the device.